Search Results (114)

The durability and fire resilience of concrete structures are increasingly critical in modern construction, particularly under elevated-temperature exposure. With this context, the current study explores the thermal and microstructural characteristics of geopolymer-based ultra-high-performance concrete (G-UHPC) incorporating quartz powder (QP) and silica fume (SF) after exposure to elevated temperatures. SF was used at 15% and 30% to partially replace the precursor material, while QP was used at 25%, 30%, and 35% as a partial replacement for fine sand. The prepared specimens were exposed to 200 °C, 400 °C, and 800 °C, followed by air cooling. Mechanical strength tests were conducted to evaluate compressive and flexural strengths, as well as failure patterns. Microstructural changes due to thermal exposure were assessed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Among the prepared mixtures, the 30SF35QP mixture exhibited the highest compressive strength (156.0 MPa), followed by the 15SF35QP mix (146.83 MPa). The experimental results demonstrated that G-UHPC underwent varying levels of thermal degradation across the 200–800 °C range yet displayed excellent resistance to thermal spalling. At 200 °C, compressive strength increased due to enhanced geopolymerization, with the control mix showing a 29.8% increase. However, significant strength reductions were observed at 800 °C, where the control mix retained only 30.8% (32.0 MPa) and the 30SF25QP mixture retained 28% (38.0 MPa) of their original strengths. Despite increased porosity and cracking at 800 °C, the 30SF35QP mixture exhibited superior strength retention due to its denser matrix and reduced voids. The EDS results confirmed improved gel stability in the 30% SF mixtures, as evidenced by higher silicon content. These findings suggest that optimizing SF and QP content significantly enhances the fire resistance and structural integrity of G-UHPC, providing practical insights for the design of sustainable, high-performance concrete structures in fire-prone environments. Full article

This study evaluated the in vitro anti-inflammatory activity of serotonin derivatives from safflower seed powder and elucidated their mechanism against ulcerative colitis using network pharmacology. Compounds were extracted and purified via silica gel column chromatography, Sephadex LH-20 and semi-preparative HPLC. Structural characterization employed NMR and UPLC-Q-TOF-MS/MS with literature comparisons. Anti-inflammatory efficacy was assessed in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Network pharmacology predicted targets, molecular docking analyzed binding interactions and molecular dynamics simulations assessed complex stability. Eleven serotonin derivatives were isolated; N-trans-Feruloyl-3,5-dihydroxyindolin-2-one (1) and Bufoserotonin A (2) were identified in safflower seed meal for the first time. Compounds 1, 3–7 and 10 significantly reduced inflammatory factors, with N-feruloyl serotonin (4, FS) showing the strongest activity. Mechanistic studies revealed FS targets key molecules (STAT3, EGFR, ESR1, PTGS2, NF-κB1, and JUN), modulating PI3K-Akt, MAPK and cancer-related pathways. Molecular dynamics simulations confirmed FS-EGFR complex stability. Thus, two novel derivatives were isolated and FS demonstrated significant anti-inflammatory and potential anti-ulcerative colitis effects through multi-target, multi-pathway synergy, providing a foundation for developing safflower seed meal therapeutics. Full article

Due to the complexity of planning and constructing underground lines, construction challenges—such as close proximity and multi-line interactions—are increasingly being recognized, along with their associated safety hazards. The visual observation of tunnel deformation and changes in the surrounding strata is difficult. In this study, laboratory model experiments were conducted using a mixture of liquid paraffin, n-tridecane, and silica gel powder, combined in specific proportions to create a transparent material that simulates natural soft rock. The new tunnel was designed to simultaneously cross over and under two existing tunnels. The impact of the new tunnel on the existing tunnels was examined, with excavation length and soil layer thickness considered as the primary influencing factors. The results indicate that excavating the new tunnel causes settlement deformation in the tunnels above and heave deformation in the tunnels below. The magnitude of deformation increases as excavation progresses but decreases with the greater thickness of the soil interlayer. For an existing tunnel, variations in the thickness of the soil interlayer not only affect its own deformation but also disturb the tunnel on the opposite side. Therefore, to ensure safer and orderly urban tunnel construction and to address the “black box” effect, it is essential to study the deformation characteristics of existing tunnels and their surrounding rock during the construction of new tunnels. Full article

The construction industry’s escalating environmental footprint, coupled with the underutilization of construction waste streams, necessitates innovative approaches to sustainable material design. This study investigates the dual functionality of recycled clay brick powder (RCBP) as both a supplementary cementitious material (SCM) and an alkali–silica reaction (ASR) inhibitor in hybrid mortar systems incorporating recycled glass (RG) and recycled clay brick (RCB) aggregates. Leveraging the pozzolanic activity of RCBP’s residual aluminosilicate phases, the research quantifies its influence on mortar durability and mechanical performance under varying substitution scenarios. Experimental findings reveal a nonlinear relationship between RCBP dosage and mortar properties. A 30% cement replacement with RCBP yields a 28-day activity index of 96.95%, confirming significant pozzolanic contributions. Critically, RCBP substitution ≥20% effectively mitigates ASRs induced by RG aggregates, with optimal suppression observed at 25% replacement. This threshold aligns with microstructural analyses showing RCBP’s Al³⁺ ions preferentially reacting with alkali hydroxides to form non-expansive gels, reducing pore solution pH and silica dissolution rates. Mechanical characterization reveals trade-offs between workability and strength development. Increasing RCBP substitution decreases mortar consistency and fluidity, which is more pronounced in RG-RCBS blends due to glass aggregates’ smooth texture. Compressively, both SS-RCBS and RG-RCBS mortars exhibit strength reduction with higher RCBP content, yet all specimens show accelerated compressive strength gain relative to flexural strength over curing time. Notably, 28-day water absorption increases with RCBP substitution, correlating with microstructural porosity modifications. These findings position recycled construction wastes and glass as valuable resources in circular economy frameworks, offering municipalities a pathway to meet recycled content mandates without sacrificing structural integrity. The study underscores the importance of waste synergy in advancing sustainable mortar technology, with implications for net-zero building practices and industrial waste valorization. Full article

Porous silica gel powders, doped with gold nanoparticles (AuNPs), were obtained by heating silica gels containing 1-dodecanethiol and tetrachloroauric acid at temperatures of 450 °C, 700 °C and 900 °C, and characterized using X-ray diffraction, TEM/EDS studies, UV/Vis reflectance spectroscopy and DTA/TG investigations. The color and microstructure of the obtained samples with a composition SiO₂:AuNPs (about 0.03% Au) depend on the heating temperature. The UV/Vis reflection spectra of the samples are explained using Mie’s theory. The thermal stability of the obtained samples, as well as the processes occurring in the sol–gel matrix upon heating, were monitored by DTA/TG. The textural properties of the obtained materials were described based on adsorption–desorption isotherms. The obtained nanocomposites are promising pigments for ceramic glazes, similar to the Purple of Cassius. The textural properties of certain samples, S_BET = 200–350 m²/g, a mean pore diameter (D_AV) of approximately 10 nm and a specific pore volume (V_t) between 0.5 and 0.8 cm³/g, make them promising candidates for catalytic applications, comparable to aerogel-like materials. Full article

Lithium orthosilicate (Li₄SiO₄) has demonstrated a high CO₂ adsorption rate and capacity and its suitability to be implemented in industry as CO₂ capture technology at high temperatures. The optimum solid adsorbent should present a porous structure to maximize surface and enable a high sorption rate. In this work, we present an original approach based on the use of a novel architecture of precursors in the form of very thin free-standing solid silica fibers. An original technique called continuous fiberizing by laser melting (Cobiflas) was used to obtain membranes of pure silica fibers with diameters in the micrometer range, forming a porous membrane which offer a high surface and porous connectivity to be used as precursors without any supporting substrate. Then, we employed a method based on the impregnation of the silica fibers within a lithium-containing aqueous solution and subsequent calcination to obtain a porous solid adsorbent with the maximum proportion of lithium orthosilicate. This method is compared with the results obtained using a sol-gel powder method by analyzing their composition using X-Ray Diffraction (XRD), and their adsorption capacity and adsorption kinetics by Thermogravimetric analyses (TGA). As a result, an outstanding type of solid adsorbent is reported with a 31% adsorption capacity and a total regeneration capacity, which is over 0.8 efficiency with regard to the theoretical maximum adsorption of this material. Full article

Diatomaceous earth (DE) consists of fossilized remnants of diatoms, which are marine or freshwater unicellular algae. Most DEs originate from fossilized sedimentary layers of diatoms deposited in water bodies during the Eocene and Miocene periods, much more than 20 million years ago. Processed DE, a soft, chalky powder, is widely used as an insecticide due to the highly absorptive and abrasive nature of its particles. As an insecticide, DE removes the wax coating of the insect epicuticle, the primary barrier against water loss. This results in water evaporation, leading to desiccation and death of the targeted insects. This review emphasizes the co-treatment of DEs with biological agents that have insecticidal properties (e.g., essential oils, plant powders, silica gel, and species/isolates of fungi), reducing the quantities used in single-application treatments and suggesting paths for the sustainable management of insects damaging stored products. Full article

Atmospheric water harvesting (AWH) is a promising alternative to address immediate water needs. Desiccant-based AWH could compete effectively with other commercially available AWH technologies. One of the primary challenges facing desiccant-based AWH is the energy required to desorb the captured water vapor from the desiccant. This work presents a multi-faceted approach targeted explicitly at low-humidity and arid regions, aiming to overcome the limitations of the refrigerant-based AWH system. It includes assessing common desiccants (zeolite, activated alumina, and silica gel) and their forms (beads, powdered, or coated on a substrate). A bench-scale test rig was designed to evaluate different types and forms of desiccants for adsorption and desorption cycles and overall adsorption capacity (g/g), kinetic profiles, and rates. Experimental results indicate that beaded desiccants possess the highest adsorption capacity compared to powdered or coated forms. Furthermore, coated desiccants double the water uptake (1.12 vs. 0.56 g water/g desiccant) and improve adsorption/desorption cycling by 52% compared to beaded forms under the same conditions. Additionally, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and dynamic vapor sorption (DVS) analysis show the pore geometry, morphology, and sorption capacity. The goal is to integrate these performance improvements and propose a more effective, energy-efficient desiccant-based AWH system. Full article

A novel extraction method based on solid-to-solid interactions has been developed to investigate the acquisition of contaminants from butyl rubber materials, with potential applications in the pharmaceutical industry. The extraction medium used is silica gel—a cost-effective, non-toxic, heat-resistant, and chemically inert material that is easy to handle in laboratory settings. Silica gel also enables straightforward recovery of adsorbed species using standard laboratory solvents. This method effectively exhausts contaminants from typical rubber articles within a reasonable timeframe, even under ambient conditions, while preserving the integrity of the material. Unlike traditional destructive liquid-based extractions, this approach produces significantly cleaner chromatographic profiles. This study focuses on the primary analytes extracted from chlorobutyl rubber, including halogenated rubber volatile impurities (VOIs), and tracks their acquisition over the course of the experiment. The findings provide valuable insights into the diffusion-based process by which pharmaceutical powders acquire contaminants, spanning a wide range of volatility and lipophilicity. Full article

Extinguishing methanol fires poses significant challenges due to methanol’s high toxicity, polarity, and fluidity. While conventional fire suppressants, such as alcohol-resistant firefighting foam, water mist and dry powders, can extinguish methanol fires, they fail to prevent the spread of liquid methanol, creating a risk of environmental contamination as the mixture of suppressants and methanol flows into surrounding soil and water resources. To address this issue, a novel kind of composite dry powder has been developed to effectively combat methanol pool fires. The powder can not only rapidly extinguish flames but also transform liquid methanol into gel-like substances, significantly reducing the hazards caused by the flow of harmful liquids. Laboratory experiments identify an optimal mass ratio of 0.16 between the composite powder and methanol to achieve complete flame extinction and liquid solidification. The superior performance of as-prepared composite powder could be mainly ascribed to the cooperation of metallic salts, polymers, and silica additives. Additionally, the powder is effective for extinguishing ethanol fires, making it a valuable tool for the emergency management of alcohol fires in leakage incidents. Full article

Calcium-silicate-based ceramic composites with different CaO/SiO₂ weight ratios (10/90, 20/80, 30/70, 40/60, 50/50, 60/40, 70/30, 80/20, and 90/10) have been prepared from chicken eggshells and silica gel using attrition milling for 3 h in wet conditions and conventional pressing–heat treatment in the air at 800 °C for 1 h. The effect of the CaO/SiO₂ weight ratio and the calcination period of the eggshells on the microstructural features including apparent density, phase evolution, and morphological properties were investigated. The phase transformation of the powder mixtures after attrition milling for 3 h in ethanol with powder/ball milling mass ratio of 0.0996 (110/1104.7) revealed to have calcium hydroxide (Ca(OH)₂) as a dominate phase, which was observed to increase with the increase in calcium oxide (CaO) amount in the powder mixtures. The phase transformation of ceramic samples after heat treatment at 800 °C for 1 h, on the other hand, showed different phases depending on the CaO/SiO₂ weight ratio. The results also show a linear relationship between the CaO/SiO₂ weight ratio and apparent density when the CaO/SiO₂ ratio increase from 0.11 (10/90) to 0.67 (40/60) due to the densification of ceramics. An inversely proportional relationship was found between CaO/SiO₂ and density when the CaO/SiO₂ weight ratio increased from 0.67 (40/60) to 9 (90/10). Full article

Adsorption chillers are distinguished by their low electricity consumption, lack of moving parts and exceptional reliability. However, their considerable weight, due to the low sorption capacity of conventional adsorbents, remains a key limitation. This study investigates the effect of introducing thermally conductive additives—aluminium powder, copper powder and graphite flakes—at 5, 15 and 25 wt.% to silica-gel-based adsorbent beds on the enhancement of heat transfer. In contrast to other works, this study also includes a novel analysis of the thermal properties of dry sorbents, since the moisture content affects the thermal conductivity. Additives improve the thermal conductivity, as measured by the laser flash method (LFA), of the bed by up to 20.7% while maintaining a reasonable sorption capacity, as measured by the dynamic vapor sorption (DVS). Additions of copper at 5–15 wt.% and graphite flakes at 15–25 wt.% provide an optimal compromise between thermal conductivity and sorption capacity. Aluminium powder, on the other hand, offers flexibility over a wider range (5–25 wt.%). The increased thermal conductivity of these modified materials is expected to lead to more efficient heat transport, which suggests the hypothesis that it could reduce the cycle time and increase the efficiency of adsorption chillers. Full article

This work deals with the synthesis of Na-P1 (GIS) zeolite using rice husk as the starting material, instead of the more expensive chemicals currently used in the industry (i.e., Na aluminates and Na silicates). Rice husk is calcined at the temperature of 550 °C to obtain rice husk ash. Na-P1 is synthesized starting from rice husk ash, NaOH, and NaAlO₂ by a protocol involving the mixing of a seed gel and a feedstock gel. Two synthesis runs are carried out at ambient pressure at the temperature of 110 °C by fixing the SiO₂/Al₂O₃ ratio at 3.5 and 5.3, respectively. The synthesized products have been identified as well as the experiments developed by X-ray diffraction and scanning electron microscopy. Then, the most successful synthesized powders were also characterized by infrared spectroscopy, Raman spectroscopy, specific surface area (BET), and differential thermal analysis. The cell parameters are calculated using the Rietveld method. The combined Rietveld and reference intensity ratio methods allows us to exclude the presence of impurities and residual amorphous phase in the conducted experiments. Testing rice husk as a source of amorphous silica in the synthesis of Na-P1 represents both economic and environmental advantages. The high yields and the results of the experiment open the way for the transfer to an industrial production scale. Full article

This study examines the effects of ultrafine recycled powder (URP) obtained from construction and demolition waste on the hydration kinetics, setting behaviour, and chemical shrinkage of Portland cement pastes. The presence of ultrafine particles in the recycled powder provides more sites for nucleation, thereby promoting the hydration process and accelerating the rate of nucleation. As a result, the setting time is reduced while chemical shrinkage is increased. Incorporating URP improves the early-age mechanical properties. When 7.5% URP is added, the highest compressive strength and flexural strength of cement mortar at a curing age of 3 d are 23.0 MPa and 3.7 MPa, respectively. The secondary hydration between the hydration product and reactive silica from URP contributes to gel formation and enhances mechanical property development. This research provides theoretical insights into utilizing recycled powder in cement-based materials and enhances our understanding of its impact on hydration kinetics. Full article

Although the most promising applications of ionogels require their contact with aqueous media, few data are available on the stability of ionogels upon exposure to water. In this paper, a simple, easy-to-setup and precise method is presented, which was developed based on the continuous conductivity measurements of an aqueous phase, to study the washout of imidazolium ionic liquids (IL) from various silica-based ionogels immersed in water. The accuracy of the method was verified using HPLC, its reproducibility was confirmed, and its systematic errors were estimated. The experimental data show the rapid and almost complete (>90% in 5 h) washout of the hydrophilic IL (1-butyl-3-methylimidazolium dicyanamide) from the TMOS-derived silica ionogel. To lower the rate and degree of washout, several approaches were analysed, including decreasing IL content in ionogels, using ionogels in a monolithic form instead of a powder, constructing ionogels by gelation of silica in an ionic liquid, ageing ionogels after sol–gel synthesis and constructing ionogels from both hydrophobic IL and hydrophobic silica. All these approaches inhibited IL washout; the lowest level of washout achieved was ~14% in 24 h. Insights into the ionogels’ structure and composition, using complementary methods (XRD, TGA, FTIR, SEM, NMR and nitrogen adsorption), revealed the washout mechanism, which was shown to be governed by three main processes: the diffusion of (1) IL and (2) water, and (3) IL dissolution in water. Washout was shown to follow pseudo-second-order kinetics, with the kinetic constants being in the range of 0.007–0.154 mol⁻¹·s⁻¹. Full article